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1. Core Guide to Tech Trees and Buildings Prioritize Headquarters (Command Center) Upgrades The level of your Headquarters dictates the cap for all buildings within your base and unlocks content. Instead of over-developing other buildings or research horizontally, make 'Meet Headquarters Requirements ➔ Level Up Headquarters' your top priority. Essential Bunker Development This is your only safety net to protect your troops and resources (especially oil) when attacked by other players. Consistently upgrading your Bunker level will prevent the disaster of losing all your troops and resources overnight.